In a digital communication system, a transmitting apparatus performs error detection encoding processes and error correction encoding processes to digital data.
Further, the digital communication system performs digital modulations to the data and outputs the data to the propagation path.
Since the data are affected by noise etc. on the propagation path, the data signals are distorted.
The receiving apparatus receives the signals from the transmitting apparatus via the propagation path, demodulates the received signals, generates likelihood data according to the signal level and decodes the generated data to obtain the original digital data.